1. Field of the Invention
This invention relates to a writing instrument which can draw fine lines without causing a blur.
2. Prior Art
Writing instruments such as fountain pens make it possible to write with a writing portion by having a structure in which ink in an ink container installed in a penholder is percolated through a bunch of fibers in a pen point receiver which is inserted into a tip end opening portion of the penholder. The ink is supplied from a tip end of the bunch of fibers to the inner surface of the tip end portion of the pen point supported by the pen point receiver. The ink is then introduced to a writing end portion of the pen point through a split formed in the middle of the tip end portion of the pen point.
In such writing instruments structured as mentioned above, the pen point is conventionally formed to curve downwardly from a center of the pen point in its width directions to both edges thereof to make an arc. The pen point is formed to have a venthole at a predetermined length of interval from the writing end portion towards a base end portion of the pen point, and to have a straight split penetrating from the venthole to the center of the writing end portion.
However, according to the above-mentioned pen point, the side fragments of the end portion divided by the split curve with respect to the width directions but they are straight in its longitudinal directions to have a two-dimensional structure. A bend-resistance of the writing end portion against a strength of the pen stroke at the time of writing is inferior. When pressure is exerted on the pen point, both of the side fragments easily warp upwards with the venthole side as a fulcrum; therefore, the split is widened and there arises a problem that the letters and lines become thicker. Therefore, although the conventional pen point may be suitable to write sentences and the like subtly adjusting thickness of letters by changing the strength of the pen stroke, it is difficult to draw an illustration with innumerable fine pieces of hair, for example.
Further, since the writing end portion is easily warped upwards by a strong pen stroke, a gap is made between the writing end portion and the pen point receiver, and letters may blur because a supply of ink from the tip end portion of a bunch of fibers for supplying ink to the pen point becomes insufficient. Furthermore, as the elastic restoration force of the writing end portion is impeded by repeatedly working bend forces at the time of writing, there is a fear that the pen point cannot be used due to a distorted state of the tip end portion of the pen point and the pen point receiver having a gap between them.
Therefore, in order to maintain the elastic restoration force for a long period of time and to resist against such repeated load as a bend force acting on the pen point at a time of writing, it is required to make a thickness of the pen point bigger, in which case it becomes impossible to draw extra fine lines.